Surface fastener manufacturing method

ABSTRACT

Molten resin is continuously extruded from an extrusion nozzle having a selected width, and at the same time, a plurality of parallel fiber filaments are introduced straightly toward the molten resin outlet in a direction along rotation of a die wheel and/or traversing one or more filaments by a predetermined width. The molten resin extruded from the extrusion nozzle and the filaments are introduced into a predetermined gap for molding a plate-like substrate sheet between the nozzle and the die wheel, which has a multiplicity of hook-forming cavities in its circumferential surface and is rotatable in one direction, and at the same time, the hook-forming cavities are filled with a part of the molten resin. The filaments are embedded in the substrate sheet of the extruded molten resin as the die wheel is driven to rotate in the direction of extrusion of the molten resin, and a plurality of hooks are continuously molded on a surface of the substrate sheet.

This is a continuation of application Ser. No. 08/359,895, filed Dec.20, 1994, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method for continuously molding a surfacefastener, which has a multiplicity of engaging members on a surface of aplate-like substrate sheet, by extruding thermoplastic resin.

2. Description of the Related Art

The technology of extruding a substrate sheet using thermoplastic resinand, at the same time, molding hooks on one surface of the substratesheet is already known by, for example, WO87/06522. The molding methoddisclosed in this publication comprises extruding molten thermoplasticresin onto a circumferential surface of a drum-shape die wheel, in whicha multiplicity of mold discs and a multiplicity of spacer plates arelaminated alternately, filling the hook-forming cavities of the molddiscs with the resin while pressing the resin on the drum surface toform a substrate sheet, and pulling molded hooks out of the cavitiesalong with the substrate sheet in timed relation to the rotation of thedrum while the resin is cooled. The mold disc has in one side surfacehook-shape cavities extending radially from the circumferential surfacetoward the center and spaced circumferentially at predetermineddistances. The side surfaces of the spacer plate are flat. The reasonwhy the spacer plate is needed is that the cavities of the whole shapeof the hook cannot be formed in a single mold.

According to the surface fastener manufacturing method disclosed in theabove-mentioned publication, since the surface fastener is merely moldedcontinuously of thermoplastic resin, it would be extended due to atension exerted on the surface fastener when it is cut into pieces, thuscausing dimensional errors in the products. Further, when the resultingsurface fastener is attached to a garment by sewing, the surfacefastener would have cracks due to the sewing needle so that it cannot besewn to the garment.

With the foregoing problems in view, it is an object of this inventionto provide a molding method for manufacturing a surface fastenereffectively and simply which is free of extension though molded ofthermoplastic resin by extrusion, is free from any crack during sewingand is stable in shape.

SUMMARY OF THE INVENTION

As the result of various studies made in order to accomplish the aboveobject, the present inventors have considered to attach a cloth, whichis woven of warp and weft yarns, to the back surface of the substratesheet, or to embed the cloth in the substrate sheet, while the substratesheet and hooks are molded integrally. In this case, however, assumingthat the characteristic of the surface fastener may be changed accordingto the yarn density, it would be necessary to prepare various kinds ofcloth having different densities. Additionally, since it is sometimesrequired to prevent the surface fastener only from being extended oronly from being cracked, it is not always necessary to give to thesurface fastener toughness in both warp and weft directions.Consequently it has turned out that using the cloth is disadvantageousfrom an economical view point and in that it might impair thecharacteristic of the surface fastener.

In other words, if the fiber filaments are used, it is possible torealize the optimum filament density simply by adjusting the number offilaments to be supplied and the speed of traverse, and it is possibleto arrange the filaments either longitudinally or transversely easily.Accordingly it has turned out that using the fiber filaments is mostadvantageous. In order to mold the substrate sheet and the hooksintegrally and to fuse the filaments of fiber material firmly with thesubstrate sheet, it is preferable to heat the filaments before joiningto the substrate sheet. If the substrate sheet is adequately melted, itis not always necessary to preheat the filaments.

According to a first aspect of the invention, the foregoing problems canbe solved by a method for continuously manufacturing a surface fastener,comprising the steps of continuously extruding molten resin from anextrusion nozzle having a selected width toward a peripheral surface ofa die wheel having a plurality of engaging-member-forming cavities formolding a plate-like substrate sheet of a predetermined width, whilefilling said cavities with a part of said molten resin, continuouslyintroducing a plurality of fiber filaments straightly and parallel ontosaid extruded molten resin and/or traversing one or more of said fiberfilaments by a predetermined width, integrating said fiber filamentswith said plate-like substrate sheet as said die wheel is driven torotate in the direction of extrusion of said molten resin, andsuccessively forming a plurality of engaging members integrally on asurface of said substrate sheet, and positively taking up said moldedsurface fastener after cooling by a suitable cooling means.

According to a second aspect of the invention, there is provided amethod for continuously manufacturing a surface fastener, whichcomprises the steps of continuously extruding molten resin from anextrusion nozzle having a selected width, continuously introducing aplurality of fiber filaments straightly and parallel in a directionalong rotation of a die wheel to an outlet of the extruded molten resinand/or traversing one or more of the fiber filaments by a predeterminedwidth, introducing the molten resin extruded from the extrusion nozzleand the filaments into a predetermined gap for molding a plate-likesubstrate sheet between the nozzle and the die wheel, which has amultiplicity of hook-forming cavities in its circumferential surface andis rotatable in one direction, and at the same time, filling theengaging-member-forming cavities with a part of the molten resin,embedding the filaments in the substrate sheet of the extruded moltenresin as the die wheel is driven to rotate in the direction of extrusionof the molten resin, successively forming a plurality of hooksintegrally on a surface of the substrate sheet, and positively taking upthe substrate sheet with the hooks molded thereon, after cooling by asuitable cooling means.

According to a third aspect of the invention, there is also provided amethod for continuously manufacturing a surface fastener, whichcomprises the steps of continuously extruding molten resin from anextrusion nozzle having a selected width, introducing the molten resininto a predetermined gap for molding a plate-like substrate sheetbetween the nozzle and a die wheel, which has a multiplicity ofhook-forming cavities in its circumferential surface and is rotatable inone direction, and at the same time, filling the engaging-member-formingcavities with a part of the molten resin, continuously introducing aplurality of parallel fiber filaments straightly onto a plate-likesubstrate sheet of the extruded molten resin, which sheet revolves alongthe rotation of the die wheel, and/or traversing one or more of thefiber filaments by a predetermined width, to thereby fixedly attach thefiber filaments to a surface of the substrate sheet, and positivelytaking up the substrate sheet with the hooks molded thereon, aftercooling by a suitable cooling means.

More specifically, in manufacturing the surface fastener according tothe first method, molten resin extruded from the extrusion nozzle isforced into a gap between the extrusion nozzle and the die wheel, andthe hook-forming cavities are progressively filled with a part of themolten resin to mold the hooks and to continuously mold a plate-likesubstrate sheet having a predetermined thickness and a predeterminedwidth. The molten resin in contact with the die wheel is guided aroundpart of the circumferential surface of the die wheel by the guideroller, during which the molten resin is cooled from the inside of thedie wheel to gradually become hard. During this hardening, as thesubstrate sheet is pulled by a suitable force in the direction ofextrusion, the individual hooks are removed smoothly from the cavity asit elastically deforms into a straight form. Immediately after that, theindividual hook restores its original shape and the resulting hook isgradually cooled to become hard.

Each of the filaments introduced to the vicinity to the outlet of theextrusion nozzle advances along the circumferential surface of the diewheel in the direction of rotation of the die wheel along the rotationof the die wheel while they are embedded in the molten resin. As aresult, the filaments are embedded in and fused with the substratesheet. The substrate sheet with the filaments and hooks integrallyformed therewith are cooled into a half-hardened state from the insideof the die wheel and then are positively taken up. At a positionimmediately downstream of the die wheel, the surface fastener will bedischarged as the surface of the substrate sheet is pressed by the guideroller.

In the resulting surface fastener, since a plurality of parallelstraight filaments arranged longitudinally of the substrate sheet crossin the substrate sheet one or more filaments meandering as traversed,the surface fastener will not be extended under tension during cuttingand will not be cracked during sewing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary vertical cross-sectional view showing a moldingapparatus for manufacturing a molded surface fastener, with backing offilaments, for carrying out a first embodiment of this invention;

FIG. 2 is a fragmentary vertical cross-sectional view showing anothermolding apparatus for carrying out a second embodiment of the invention;

FIG. 3 is a fragmentary plan view showing an example of surface fastenermanufactured according to the first embodiment;

FIG. 4 is a cross-sectional view taken along line A--A of FIG. 3;

FIG. 5 is a plan view showing an example of arrangement of filamentsaccording to this invention;

FIG. 6 is a plan view showing another example of arrangement offilaments; and

FIG. 7 is a plan view showing still another example of arrangement offilaments.

DETAILED DESCRIPTION

Embodiments of this invention will now be described in detail withreference to the accompanying drawings.

FIG. 1 is a fragmentary vertical cross-sectional view showing a surfacefastener, in which fiber filaments are fixed to the back surface of asubstrate sheet longitudinally and transversely and engaging members aremolded on the front surface of the substrate sheet, as manufactured onan apparatus according to a first embodiment of this invention. In thefirst embodiment and a second embodiment described later, the engagingmembers are hooks. However, the shape of the engaging members should byno means be limited to hooks but they may have different shape such asanchor etc.

In FIG. 1, reference numeral 1 designates an extrusion nozzle; the upperhalf of an end surface of the nozzle 1 is an arcuate surface 1a having acurvature virtually equal to that of a die wheel 2 described below,while the lower half end surface is an arcuate surface 1b having apredetermined gap between the arcuate surface 1b and a curved surface ofthe die wheel 2 for molding a plate-like substrate sheet 4a. Theextrusion nozzle 1 is a T-type die, from an outlet 1d of which moltenresin 4 is to be extruded in the form of a sheet. According to thisembodiment, the extrusion nozzle 1 has a centrally extending passageway1c.

The die wheel 2 is positioned in such a manner that part of itscircumferential surface is close to the upper arcuate surface 1a and isspaced a predetermined gap from the lower arcuate surface 1b, and thatits axis is parallel to the outlet 1d. The circumferential surface ofthe die wheel 2 has a multiplicity of hook-forming cavities 5. Since thestructure of the die wheel 2 is substantially identical with thestructure disclosed in WO87/06522, it is described here briefly. The diewheel 2 is in the form of a hollow drum having in it a water coolingjacket 2a. Centrally in the hollow drum, a multiplicity of ring-shapeplates are laminated along the axis of the hollow drum. Each of everyother ring-shape plates has in the front and back surfaces amultiplicity of hook-forming cavities 5 with the base of each hookopening to the circumferential surface of the drum. Both the front andback surfaces of each of non-illustrated ring-shape plates adjacent tothe ring-shape plate having the hook-forming cavities 5 are flat. Thedie wheel 2 is rotatable, in a direction indicated by an arrow, asdriven by a non-illustrated known drive unit.

A plurality of fiber filaments F are introduced into the gap between theupper arcuate surface 1a and the circumferential surface of the diewheel 2 via a plurality of parallel filament guides 8 arrangedtransversely of the extrusion nozzle 1. As shown in FIG. 1, a firstfilament guide 8a indicated by solid lines is fixed to, for example, anon-illustrated frame and guides the filaments F straightly so as tofeed them in the direction of rotation of the die wheel 2. A secondfilament guide 8b indicated by phantom lines in FIG. 1 isreciprocatingly moved by a predetermined width of traverse in adirection parallel to the axis of the die wheel 2 by a traverse devicewhich is widely used in the field of textile machines. Accordingly thefilaments F guided by the second filament guide 8b will be introducedinto the gap between the upper arcuate surface 1a and thecircumferential surface of the die wheel 2, meandering over apredetermined width of traverse. Likewise the first filament guides 8a,a plurality of second filament guides 8b are arranged parallel to oneanother and have each a desired width of traverse so that variouscomposite meandering patterns can be obtained, by synchronous traverse,as shown in FIGS. 5 through 7. Further, by varying the traverse speed,it is possible to vary as desired the distance of the filaments arrangedin the direction of rotation of the die wheel 2.

Further, in front (on the right side in FIG. 1) of the die wheel 2, aguide roller 9 is situated, and in front of the guide roller 9, a set ofupper and lower discharge rollers 6, 7 is situated.

The resin material and the fiber filament material to be used in thisinvention are exemplified by thermoplastic resin such as nylon,polyester and polypropylene. The resin material and the filamentmaterial may be identical with or different from each other. During themolding, the molten resin temperature, extrusion pressure, die wheeltemperature, speed of rotation of the die wheel, etc. should of coursebe controlled in accordance with the material used.

According to the apparatus constructed as mentioned above, molten resin4 extruded from the extrusion nozzle 1 is forced into the gap betweenthe extrusion nozzle 1 and the die wheel 2 in rotation, and a part ofthe extruded molten resin 4 is gradually charged in the hook-formingcavities 5 to mold hooks 4b and to continuously mold the plate-likesubstrate sheet 4a having a predetermined thickness and a predeterminedwidth. The molded substrate sheet and hooks 4a, 4b are moved aroundsubstantially a half of the circumferential surface of the die wheel 2as guided by the guide roller 9, during which they are cooled from theinside of the die wheel 2 to gradually become hard. During thishardening, when the molded substrate sheet 4a is pulled in the directionof extrusion by a suitable force, the individual hooks 4b are removedsmoothly from the cavities 5 as they elastically deform into a straightform. Immediately after that, the hooks 4b restore their original shapeand hence are gradually cooled to become hard.

The individual filaments F introduced to the vicinity to the outlet 1bof the extrusion nozzle 1 advance along the circumferential surface ofthe die wheel 2 in the direction of rotation of the die wheel 2 alongthe rotation of the die wheel 2 while they are embedded in the moltenresin. As a result, the filaments F are embedded in and fused with thesubstrate sheet 4a as shown in FIGS. 3 and 4. The substrate sheet 4awith the filaments F fused therewith and the hooks 4b are cooled into ahalf-hardened state from the inside of the die wheel 2 and then arepositively taken up. At a position immediately downstream of the diewheel 2, the surface fastener is discharged as the surface of thesubstrate sheet 4a is pressed by the guide roller 9.

In this embodiment, in order to remove the resin molded product (surfacefastener with backing of filaments) from the die wheel 2, a set of upperand lower discharge rollers 6, 7 rotatable in opposite directions insynchronism with each other is used. Although the circumferentialsurfaces of the discharge rollers 6, 7 may be smooth, it is preferablethat they have grooves for receiving the rows of hooks 4b so that thehooks 4b are kept from being damaged. The rotating speed of thedischarge rollers 6, 7 is determined to be slightly larger than therotating speed of the die wheel 2 so that the hooks 4b can be removedsmoothly from the hook-forming cavities 5.

In the resulting surface fastener, since a plurality of parallelstraight filaments F arranged longitudinally of the substrate sheet 4across in the substrate sheet 4a one or more filaments F meandering astraversed, the surface fastener will not be extended under tensionduring cutting and will not be cracked during sewing.

FIG. 2 shows an apparatus for manufacturing a surface fastener withbacking of filaments according to a second embodiment, in which thefilament guide section of the first embodiment is modified. In thesecond embodiment, parts or elements substantially identical with thoseof the first embodiment are designated by like reference numerals.

In FIG. 2, reference numeral 3 designates a filament pressure rollersituated under the extrusion nozzle 1 so as to simultaneously press themolten resin and filaments F against part of the circumferential surfaceof the die wheel 2. The first filament guide 8a, which guides thefilaments F straightly in the direction of rotation of the die wheel 2,is situated under the filament pressure roller 3. The first filamentguide 8a guides the filaments F in such a manner that the filament Fgoes around part of the circumferential surface of the filament pressureroller 3 and then supplies them to the gap between the pressure roller 3and the die wheel 2. The second filament guide 8b is situatedimmediately upstream side of the resin pressing point between the diewheel 2 and the pressure roller 3, and likewise the first embodiment,supplies the filaments F while traversing by a predetermined width oftraverse in the direction parallel to the axis of the die wheel 2.

Therefore, in the second embodiment, the upper arcuate surface 1a of thenozzle 1 has a curvature virtually equal to that of the die wheel 2,while the lower arcuate surface 1b has a predetermined gap for moldingthe substrate sheet 4a between itself and the circumferential surface ofthe die wheel 2. The extrusion nozzle 1 is the T-type die having thepassageway 1c with the outlet 1d in the boundary of the upper and lowerarcuate surfaces 1a, 1b, from which outlet 1d molten resin 4 is to beextruded in the form of a sheet.

According to the second embodiment, the molten resin extruded from theextrusion nozzle 1 is introduced into the gap defined between theextrusion nozzle 1 and the die wheel 2 and then fills the hook-formingcavities 5, which are provided in the circumferential surface of the diewheel 2, gradually along the rotation of the die wheel 2. The moltenresin on the die wheel 2 is moved around virtually a quarter of thecircumferential surface of the die wheel 2 and then is removed from thedie wheel 2, while being gradually cooled by a non-illustrated coolingdevice inside the die wheel 2.

During this molding, the filaments F are guided simultaneously by thefirst and second filament guides 8a, 8b and are then fused integrallywith the surface of the substrate sheet 4a, which are formed on thecircumferential surface of the die wheel 2, as the filaments F arepressed against the surface of the substrate sheet 4a. At that time, ifthe filaments F are heated previously, there should be no difference intemperature between the filament F and the half-molten high-temperaturesubstrate sheet 4a, thus causing reliable fusing.

As mentioned above, in the surface fastener manufactured according toeach of the foregoing embodiments, a multiplicity of hooks 4b are moldedon the surface of the substrate sheet 4a, and the filaments F arearranged at desired distances longitudinally and transversely in thesubstrate sheet 4a as being fused with the substrate sheet 4a. However,this invention should be no means be limited to the foregoingembodiments, and it should not be necessary to arrange the filaments Fin both the longitudinal and transverse directions, depending on thecharacteristic of the required surface fastener. A pair of traversefilaments F may be used as shown in FIG. 7, without arranging straightfilaments F. Alternatively, only the straight filaments F may bearranged longitudinally of the substrate sheet 4a.

In the foregoing embodiments, as is apparent from FIGS. 3 and 4, amultiplicity of rows of hooks 4b are formed on the surface of thesubstrate sheet 4a and each of the hooks 4b has a pair of ribs 4c one oneach of opposite side surfaces. In the same hook row, the hooks 4b aredirected in a common direction, and in the adjacent hook rows, they aredirected in mutually opposite directions. Although they may be omitted,the ribs 4c are effective in preventing the hooks 4b from falling flat.In this invention, in the same hook row, the adjacent hooks 4b may bedirected in mutually opposite directions so that a surface fastenerhaving no direction in coupling can be obtained. Various modificationsmay be suggested within the scope and concept of this invention.

As is explained above in detail, according to the molding method of thisinvention, various kinds of molded surface fasteners, in which filamentsare arranged in the substrate sheet in various patterns can becontinuously manufactured simply in a single process without requiringmeticulous processes. The direction of engagement of the resultingsurface fastener can be selectively secured among only longitudinal,only transverse and both, depending on the arrangement of the filaments.This surface fastener is excellent in dimensional precision and is freefrom being extended when it is cut into pieces in a subsequent step.Also in the sewing step, the surface fastener is free from any crack inthe substrate sheet due to the sewing needle. Accordingly a durable andhigh-quality surface fastener can be obtained.

In the above-described embodiments, the molten resin is extruded towardthe die wheel in a direction right-angled to the peripheral surface ofthe die wheel. Alternatively, the molten resin may be extruded betweenan upper die wheel and a lower press wheel both of which co-rotate inopposite directions.

What is claimed is:
 1. A method for continuously manufacturing a surfacefastener, comprising:(a) continuously extruding molten resin from anextrusion nozzle having a selected width toward a peripheral surface ofa die wheel having a plurality of engaging-member-forming cavities formolding a plate shaped substrate sheet having a selected width, whilefilling said cavities with a part of said molten resin; (b) continuouslyintroducing a plurality of individual, spaced apart, elongate,continuous fiber filaments into said extruded molten resin downstream ofsaid extrusion nozzle; (c) integrating said fiber filaments with saidplate shaped substrate sheet as said die wheel is driven to rotate inthe direction of the extrusion of said molten resin, and successivelyforming a plurality of engaging members integrally on a surface of saidsubstrate sheet; and (d) positively taking up said molded surfacefastener after cooling by a suitable means, said fiber filamentspreventing the surface fastener from being extended during cuttingand/or from being cracked during sewing.
 2. The method according toclaim 1, wherein the step of introducing the fiber filaments is furtherdefined in that the fiber filaments are introduced in a straight andparallel pattern.
 3. The method according to claim 1, wherein the stepof introducing the fiber filaments is further defined in that the fiberfilaments are introduced in a traversing pattern across a selectedwidth.
 4. The method according to claim 1, wherein the step ofintroducing the fiber filaments is further claimed in that the fiberfilaments are introduced with some fiber filaments running in a straightparallel pattern and respective other fiber filaments are introduced ina traversing pattern across a selected width.
 5. A method forcontinuously manufacturing a surface fastener, comprising:(a)continuously extruding molten resin from an extrusion nozzle having aselected width; (b) continuously introducing a plurality of individual,spaced apart, elongate, continuous fiber filaments in a direction alongrotation of a die wheel upstream of an outlet of said extruded moltenresin; (c) introducing said molten resin extruded from said extrusionnozzle and said filaments into a predetermined gap for molding a plateshaped substrate sheet between said nozzle and the die wheel, which hasa multiplicity of engaging-member-forming cavities in itscircumferential surface and is rotatable in one direction, and at thesame time, filling said engaging-member-forming cavities with a part ofsaid molten resin; (d) embedding said filaments in said plate shapedsubstrate sheet of extruded molten resin as said die wheel is driven torotate in the direction of extrusion of said molten resin, andsuccessively forming a plurality of engaging members integrally on asurface of said substrate sheet; and (e) positively taking up saidsubstrate sheet with said engaging members molded thereon, after coolingby a suitable cooling means, said fiber filaments preventing the surfacefastener from being extended during cutting and/or from being crackedduring sewing.
 6. The method according to claim 5, wherein the step ofintroducing the fiber filaments is further defined in that the fiberfilaments are introduced in a straight and parallel pattern.
 7. Themethod according to claim 5, wherein the step of introducing the fiberfilaments is further defined in that the fiber filaments are introducedin a traversing pattern across a selected width.
 8. The method accordingto claim 5, wherein the step of introducing the fiber filaments isfurther claimed in that the fiber filaments are introduced with somefiber filaments running in a straight parallel pattern and respectiveother fiber filaments are introduced in a traversing pattern across aselected width.
 9. A method for continuously manufacturing a surfacefastener, comprising:(a) continuously extruding molten resin from anextrusion nozzle having a selected width; (b) introducing said moltenresin into a predetermined gap for molding a plate shaped substratesheet between said nozzle and a die wheel, which has a multiplicity ofengaging-member-forming cavities in its circumferential surface and isrotatable in one direction, and at the same time, filling saidengaging-member-forming cavities with a part of said molten resin; (c)continuously introducing a plurality of individual, elongate, continuousparallel spaced apart fiber filaments into said plate shaped substratesheet of said extruded molten resin, which sheet revolves along therotation of said die wheel, to thereby fixedly attach said fiberfilaments to a surface of said substrate sheet; and (d) positivelytaking up said substrate sheet with the engaging members molded thereon,after cooling by a suitable cooling means, said fiber filamentspreventing the surface fastener from being extending during cuttingand/or from being cracked during sewing.
 10. The method according toclaim 9, wherein the step of introducing the fiber filaments is furtherdefined in that the fiber filaments are introduced in a straight andparallel pattern.
 11. The method according to claim 9, wherein the stepof introducing the fiber filaments is further defined in that the fiberfilaments are introduced in a traversing pattern across a selectedwidth.
 12. The method according to claim 9, wherein the step ofintroducing the fiber filaments is further claimed in that the fiberfilaments are introduced with some fiber filaments running in a straightparallel pattern and respective other fiber filaments are introduced ina traversing pattern across a selected width.